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Higher Study | Environmental Engineering | Water Treatment

Which out of the following does not help in disinfecting water?
How much bleaching powder (having 20% available chlorine) is needed to disinfect 10,000 litres of water whose chlorine demand is 1.0 mg/l? It should  be ensured that, after about 1 hour contact time, 0.2 mg/l chlorine is available.
Determine the quantity of bleaching powder required for a rural water supply scheme so as to chlorinate 20000 litre of water, whose chorine demand is 2 mg/l. Assume the bleaching powder has 50 % available chlorine.
Why is proportional flow weir provided in a grit chamber ?
Sedimentation with coagulation treatment of water is effective when water is
The question consists of two statements, one labelled as ‘Assertion (A)’ and the other as ‘Reason (R)’: Assertion (A): Tapered flocculation is more efficient when compared to the conventional process of flocculation. Reason (R): In tapered flocculation, velocity gradient at the inlet is less than that at the outlet of the flocculation unit. Examine above two statements carefully and select the correct answer from the option given below: 
Air binding in rapid sand filters is encountered when
Alum as a coagulant is found to be most effective when the pH range of water is
Boiling of water or adding lime in water will remove the hardness of water when it is due to:
What will happen when the alum is mixed with water as coagulant?
When a turbid stream flows into the ocean, the ionic content of the water increases drastically. This causes coagulation and settling which leads to formation of deposits (deltas). Such coagulation mechanism is called:
When chlorine is dissolved in water, it reacts to form hypochlorous acid and hypochlorite ions. At pH < 5, chlorine exists in water as
Consider the following statements regarding coagulant aids: 1. They are employed when temperature is low as they then accelerate the process of coagulation. 2. They are employed when flocs are small and water is coloured. 3. With their use, water purification capacity of the plant is increased. 4. Most widely used materials are oxidants absorbents, weighing agents, activated carbon and polyelectrolytes. Which of the above statements are correct?
Statement I): Incrustation of sand occurs in rapid sand filter when water softened by lime-soda is fed in for filtration. Statement II): The sand gets coated with precipitates of Ca(OH)2 and Mg(OH)2 generated during softening of water by lime-soda process which leads to incrustation of sand.
A water treatment plant of capacity, 1 m3/s has filter boxes of dimensions 6 m × 10 m. The loading rate to the filters is 120 m3/day/m2. When two of the filters are out of service for back washing, the loading rate (in m3/day/m2) is
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